First-principles calculations to investigate thermodynamic and mechanical behaviors of molybdenum-lanthanum alloy

Abstract

ABSTRACT Using first-principles calculations, we have performed the detailed researches on La behavior in Mo including structure, thermodynamic stability, interaction with vacancy, and mechanical properties of Mo-La alloy. La prefers to stay at substitution site with the solution energy of 2.86 eV. The <111> mixed dumbbell is more stable than both <100> and <110> mixed dumbbells. The La-La interaction displays attraction and repulsion in short- and long-distance range, respectively. Both 1nn and 2nn shells are most likely to form the La-La clusters since there are relatively larger binding energies, which are 0.43 and 0.33 eV, respectively. The La-vacancy interaction is much local and limited within the 2nn shell range. At 1nn and 2nn shells, the binding energies of La-vacancy are 1.33 and 0.26 eV, respectively. Also, the mechanical properties of Mo1-xLax (0 < x < 0.1) binary alloys have been analyzed in detail. The mechanical quantities of single crystal are the elastic constants, Young’s modulus and shear modulus, while the mechanical quantities of poly-crystal include bulk modulus B, Young’s modulus E, shear modulus G, Poisson’s ratio v, Anisotropy factor A and B/G. These results can provide a much valuable reference for Mo-alloy application in nuclear fusion field.